The semiconductor integrated circuit (IC) industry has experienced rapid growth. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. However, such scaling down has also been accompanied by increased complexity in design and manufacturing of devices incorporating these ICs, and, for these advances to be realized, similar developments in device fabrication are needed.
As merely one example, multi-gate devices have been introduced in an effort to improve gate control, reduce OFF-state current, and reduce short-channel effects by increasing gate-channel coupling. One such multi-gate device that has been introduced is the fin field-effect transistor (FinFET). The FinFET gets its name from the fin-like structure which extends from a substrate on which it is formed, and which is used to form the FET channel. FinFETs are compatible with conventional complementary metal-oxide-semiconductor (CMOS) processes and their three-dimensional structure allows them to be aggressively scaled while maintaining gate control and mitigating short-channel effects. However, continued scaling of FinFET devices requires concurrent improvements in photolithographic processes. Current lithography techniques may be limited, for example, in their alignment precision and repeatability of the equipment used (e.g., a photolithography stepper), as well as in the minimum feature size that may be printed. Thus, current lithography tools may not provide sufficient process margin, in particular when employing existing photolithography processes. As a result, FinFET critical dimensions (CDs) may be directly impacted by pattern misalignment, or other lithography errors, which can result in degraded device performance and/or device failure. Thus, existing techniques have not proved entirely satisfactory in all respects.